Portion of a display screen showing a user interface



The FIGURE is a front view showing the new design.

The broken lines in the Figure represent unclaimed features and form no part of the claimed design. The broken lines illustrating a portion of a display screen are for illustrative purposes only and form no part of the claimed design. The broken lines illustrating “CONTENT” are for illustrative purposes only and form no part of the claimed design. 

The ornamental design for a portion of a display screen showing a user interface, as shown and described. 